selftests/mm: gup_test: stop testing FOLL_TOUCH

selftests/mm: gup_test: stop testing FOLL_TOUCH

commit 0f20bba1688b ("mm/gup: explicitly define and check internal GUP
flags, disallow FOLL_TOUCH") marked FOLL_TOUCH as a GUP-internal flag.

This causes a warning to fire when running gup_test, for example:

    $ ./gup_test -L -r 100 -z

dmesg:
    WARNING: CPU: 1 PID: 117 at mm/gup.c:2512 is_valid_gup_args+0x66/0x8c

Therefore, remove the "FOLL_TOUCH" test code from gup_test.c.

Link: https://lkml.kernel.org/r/20251117154012.197499-1-peng8420.li@gmail.com
Signed-off-by: Peng Li <peng8420.li@gmail.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>